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Date: Fri, 7 Mar 2014 01:39:45 +0530 From: Nilesh More <nilesh99999@...il.com> To: linux-kernel@...r.kernel.org Subject: Re: Reporting a bug - Memory corruption in Linux kernel Hi all, I am working on android bug wherein directory entries of ext4 file system get corrupted when USB is hotplugged (with auto mount support enabled). The logs as below: [ 413.607849] usb 2-1.1: USB disconnect, device number 12 [ 414.022630] EXT4-fs error (device mmcblk0p20): ext4_readdir:227: inode #81827: block 328308: comm installd: path /data/data/com.android.nfc/shared_prefs: bad entry in directory: rec_len is smaller than minimal- offset=0(0), inode=0, rec_len=0, name_len=0 [ 414.045204] Aborting journal on device mmcblk0p20-8. [ 414.051217] Kernel panic- not syncing: EXT4-fs (device mmcblk0p20): panic forced after error [ 414.051217] [ 414.061199] CPU: 0 PID: 150 Comm: installd Not tainted 3.10.24-gfe0c16e-dirty #1 [ 414.068586] [<c0016ae8>] (unwind_backtrace+0x0/0x140) from [<c0012e94>] (show_stack+0x18/0x1c) [ 414.077181] [<c0012e94>] (show_stack+0x18/0x1c) from [<c0853b7c>] (panic+0x94/0x1ec) [ 414.084909] [<c0853b7c>] (panic+0x94/0x1ec) from [<c01eb634>] (ext4_handle_error+0x70/0xac) [ 414.093241] [<c01eb634>] (ext4_handle_error+0x70/0xac) from [<c01eb7d4>] (ext4_error_file+0xc8/0x128) [ 414.102443] [<c01eb7d4>] (ext4_error_file+0xc8/0x128) from [<c01cbcdc>] (__ext4_check_dir_entry+0xe8/0x188) [ 414.112163] [<c01cbcdc>] (__ext4_check_dir_entry+0xe8/0x188) from [<c01cc130>] (ext4_readdir+0x3b4/0x800) [ 414.121709] [<c01cc130>] (ext4_readdir+0x3b4/0x800) from [<c0155514>] (vfs_readdir+0x98/0xbc) [ 414.130215] [<c0155514>] (vfs_readdir+0x98/0xbc) from [<c0155678>] (SyS_getdents64+0x6c/0xd4) [ 414.138721] [<c0155678>] (SyS_getdents64+0x6c/0xd4) from [<c000ef80>] (ret_fast_syscall+0x0/0x30) While I tried to root cause this issue - at the time of USB disk mount, I see lot of block_invalidatepage calls through the call stack : add_disk->register_disk->blkdev_put->kill_bdev->truncate_inode_page-->block_invalidatepage If I prevent kill_bdev from invalidating pages, I see a No-Repro for this bug. Also there are no prints saying invalid access to FAT entry(which were present when bug reproduces). Earlier we had no-repro when added delay(1) before _getblk. This points out to the loss of sync between _getblk and kill_bdev and ALSO looks like kill_bdev inadvertently invalidates pages which are Ext4 owned. I am going to debug further to try and get to root cause. Before that wanted to ask if is this A KNOWN ISSUE ? If not, any suggestions that would help me to quickly root cause this ? Thank you for your help, Nilesh On Fri, Mar 7, 2014 at 1:35 AM, Nilesh More <nilesh99999@...il.com> wrote: > Hi all, > > I am working on android bug wherein directory entries of ext4 file system > get corrupted when USB is hotplugged (with auto mount support enabled). > > The logs as below: > [ 413.607849] usb 2-1.1: USB disconnect, device number 12 > [ 414.022630] EXT4-fs error (device mmcblk0p20): ext4_readdir:227: inode > #81827: block 328308: comm installd: path > /data/data/com.android.nfc/shared_prefs: bad entry in directory: rec_len is > smaller than minimal- offset=0(0), inode=0, rec_len=0, name_len=0 > [ 414.045204] Aborting journal on device mmcblk0p20-8. > [ 414.051217] Kernel panic- not syncing: EXT4-fs (device mmcblk0p20): panic > forced after error > [ 414.051217] > [ 414.061199] CPU: 0 PID: 150 Comm: installd Not tainted > 3.10.24-gfe0c16e-dirty #1 > [ 414.068586] [<c0016ae8>] (unwind_backtrace+0x0/0x140) from [<c0012e94>] > (show_stack+0x18/0x1c) > [ 414.077181] [<c0012e94>] (show_stack+0x18/0x1c) from [<c0853b7c>] > (panic+0x94/0x1ec) > [ 414.084909] [<c0853b7c>] (panic+0x94/0x1ec) from [<c01eb634>] > (ext4_handle_error+0x70/0xac) > [ 414.093241] [<c01eb634>] (ext4_handle_error+0x70/0xac) from [<c01eb7d4>] > (ext4_error_file+0xc8/0x128) > [ 414.102443] [<c01eb7d4>] (ext4_error_file+0xc8/0x128) from [<c01cbcdc>] > (__ext4_check_dir_entry+0xe8/0x188) > [ 414.112163] [<c01cbcdc>] (__ext4_check_dir_entry+0xe8/0x188) from > [<c01cc130>] (ext4_readdir+0x3b4/0x800) > [ 414.121709] [<c01cc130>] (ext4_readdir+0x3b4/0x800) from [<c0155514>] > (vfs_readdir+0x98/0xbc) > [ 414.130215] [<c0155514>] (vfs_readdir+0x98/0xbc) from [<c0155678>] > (SyS_getdents64+0x6c/0xd4) > [ 414.138721] [<c0155678>] (SyS_getdents64+0x6c/0xd4) from [<c000ef80>] > (ret_fast_syscall+0x0/0x30) > > > While I tried to root cause this issue - at the time of USB disk mount, I > see lot of block_invalidatepage calls through the call stack : > add_disk->register_disk->blkdev_put->kill_bdev->truncate_inode_page-->block_invalidatepage > > If I prevent kill_bdev from invalidating pages, I see a No-Repro for this > bug. Also there are no prints saying invalid access to FAT entry(which were > present when bug reproduces). Earlier we had no-repro when added delay(1) > before _getblk. > > This points out to the loss of sync between _getblk and kill_bdev and ALSO > looks like kill_bdev inadvertently invalidates pages which are Ext4 owned. > > I am going to debug further to try and get to root cause. Before that wanted > to ask if is this A KNOWN ISSUE ? If not, any suggestions that would help > me to quickly root cause this ? > > Thank you for your help, > Nilesh -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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